On 2005-11-11, Jim wrote:

I do not want to punch ar hole in my roof unless it is absolutely
necessary for obvious reasons. I really do not want another 4 inch
pvc pipe sticking out of my roof.

The usual roof termination for a bathroom exhaust fan is quite short,
it's not an exposed pipe. An exposed pipe would allow rain into the
vent, a bad idea. [Doesn't matter for the sewer, though!] See, for
example http://www.broan.com/display/router.asp?ProductID=2925.

Cheers Wayne